Many mixing valves have a control stem mounted to an operable handle that controls the mix of hot and cold water to the outlet port in a faucet. Often the control stem that controls the temperature mix is separate from the flow rate control portion of the faucet. As such, the temperature-mixing device can be located significantly upstream and removed from the flow rate control valve and the spout or final outlet port. Remote mixing valves are often used in conjunction with a bank of electronic faucets which turn on and off by sensing the presence of a persons hands or body. The electronic sensing device controls the on-off position and the flow rate of the valve but often does not control the mix of the hot and cold water. The hot and cold water supplies are premixed to a desired temperature upstream.
As such, the temperature-mixing valve is often concealed to prevent the casual user or unauthorized person from tampering with or inadvertently changing the temperature mix. While many of these mixing valves may be behind closed doors and remote from the faucet, they still have freely accessible handles, which may be easily and inadvertently changed.
What is needed is a temperature-mixing valve with a knob that can be easily locked in place to prevent casual tampering or inadvertent adjustment but can be readily released with a special tool to provide adjustment to the desired temperature.